1. Field of the Invention
The present invention relates to an image forming apparatus capable of starting a function required by a user in response to an instruction from the user.
2. Description of the Related Art
In recent years, with the increasing concern about the global environmental issues, reduction of power consumption in image forming apparatuses such as copying machines have attracted a lot of attention. In view of this, many image forming apparatuses shift to a power-saving mode on condition that a print request is not received for a certain period of time, for example. Then, power supply used for a heater is stopped or power supply to a CPU for control and a memory used for the CPU is stopped, for example, so as to reduce power consumption. On the other hand, a time for returning from such a power-saving mode is naturally desired to be shorter in terms of convenience.
Conventionally, the returning time from the power-saving mode has been most dependent on a warm-up time for a fuser when the fuser reaches a temperature enabling image formation. However, with the advancement of techniques for warming up the fuser in a short period of time, the warming-up of the fuser is completed in a short period of time. Nowadays, time required for a warm-up operation such as a preliminary operation and the like in units other than the fuser poses a new problem. In other words, the warm-up operation limits reduction of a start-up time for an entire image forming apparatus. Specifically, unless the preliminary operation of other units such as a communication initialization operation in a control unit, for example, is completed, it is impossible to start the warm-up operation of the fuser.
Patent Documents 1 and 2 disclose inventions as techniques for resolving such a problem, for example. An invention disclosed in Patent Document 1 includes a heater, a first switching element turning on and off electricity from a power supply for heating the heater, a first hardware control circuit switching on and off the switching element by hardware control, a computer operating based on a predetermined program, and a control unit switching on and off the switching element by software control in accordance with a process performed by the computer instead of the hardware control after the computer is initialized. The electric supply to the heater is started without waiting for the computer performing the software control to be initialized, so that it is possible to quickly heat the heater.
An invention disclosed in Patent Document 2 relates to an image forming device for forming an image in which an electrostatic latent image formed on an electrostatic latent image carrier is developed and visualized using a developer layer carried on a developer carrier, a visualized image is transferred to a recording medium, and a toner image transferred on the recording medium is fixed by a fuser unit. The image forming apparatus includes at least two of a copying machine function, printer function, and facsimile machine function. The image forming apparatus includes a warm-up control unit performing a warm-up operation only on a structure relating to a function selected by a user or a function for which job is input upon powering on or returning from a long period of non-performing status through a user operation input or a job input. In accordance with this, it is possible to reduce time to wait for an image of the selected job to be output and to reduce quantity of electricity and conserve energy in an entire apparatus.
Patent Document 1: Japanese Laid-Open Patent Application No. 2004-265650
Patent Document 2: Japanese Laid-Open Patent Application No. 2005-297264
In the invention disclosed in Patent Document 1, the electric supply to the heater is started without waiting for the computer performing the software control to be initialized, so that it is possible to quickly heat the heater. However, in this case, only the initialization of the computer is handled, so that when an element other than the computer, namely, a communication function unit as hardware is not started, for example, the heater is not heated and it is impossible to reduce the start-up time.
Further, in the invention disclosed in Patent Document 2, when only the function selected by the user is used, the start-up time is reduced. However, when plural instructions are input at one time or when a main power supply of the image forming apparatus is switched on, namely, when starting the entire image forming apparatus, it is impossible to reduce the start-up time. In other words, the method disclosed in Patent Document 2 only starts the function selected by the user, so that the start-up time is reduced in comparison with a time to start all the functions of the image forming specification. However, the start-up time is not reduced when all the functions are started at one time. Further, in the invention disclosed in Patent Document 2, a time of operation required to start a function to be used is not changed. For example, a time of an initialization operation (software process and the like) upon establishing communication between a control unit and a relevant function unit of the image forming apparatus is not changed. Accordingly, a start-up time for each function block per se is not reduced.